Fluid pressure control mechanism



INVENTOR. YwizffedA. Edo/b. B

J f Gliorneys W. A. EATON FLUID PRESSURE CONTROL MECHANISMv Filed April 27, 1945 May ll, 1948.

Patented May l1, T1948 FLUID PRESSURE CONTROL MECHANISM Wilfred A. Eaton, Elyria, Ohio, assignor to Bendix-Westinghouse Automotive Air Braker Com- I pany, Elyria, Ohio, a corporation of Delaware Application April 27, 1945, serial No. 590,673`

Claims. l

This invention relates in general to power means for controlling the operation of a remotely positioned device, and more particularly to fluid pressure control mechanism for .controlling the operation of a remotely positioned rudder or other device on a vehicle such as a boat or airplane.

One of the objects'of. the present invention is to provide power operated means for effecting a graduating control of the movement of a remotely positioned rudder or device.

Another object of the invention is to'provide novel locking means for insuring maintenance of the device in any desired position regardless of any outside force applied to the device.

Yet another object of the invention is to provide, in a mechanism of the above type, locking means for the' device so constituted as to be controlled by vvariations in the degree of power supplied to various portions of the mechanism.

A still further object of the invention is to piovide, in connection with a power operated mechanism wherein a compressible iiuid is utilized as the power medium, meanscontrolled by the application of the compressible medium lto the mechanism for positively eiiecting locking of the device in any desired-position. l

These and other desirable objects and features of the invention will be readilyapparent to those skilled in the art when considered in the light of the-'following description', but it is to be expressly understood that the description is not to be taken as limiting the invention, reference being had for this'purpose to the appended claims.

In the drawing, the single figure illustrates diagrammatically, and partially in section, a fluid pressure control mechanism constructed in accordance with the principles of the present invention.

Referring to the drawing, the mechanism includes in general, a fluid pressure reservoir 4, an operators control valve mechanism 5, a pair of double acting actuators or cylinders 5 and l, control valvemechnism 8, a remotely positioned rudder or device to be -actuated 9, a mechanism Il),` adapted to normally maintain the device 9 in neutral position, ahydraulic locking device orcylinder I I-, to'be more fully described hereinafter, andfa hydraulic control valve mechanism |21 adapted to control the action of the hydraulic locking device I I.

The reservoir 4 is adapted to receive uid pressure from a compressor, not shown, through a'conduit I3, and is adapted to supply uuid pressure to inlet chambers I4 and I5 of the o-perators 4control valve mechanism 5 through conduits I6 and I l, and to supply iiuid pressure to an' inlet chamber I8 provided in the control valve mechanism 8 through a conduit I9 and a flexible conduit or hose 20. The valve mechanism 5, tobe described hereinafter in more detail, is provided with valve operating plungers 2I and 22, and outlet conduits 23 and 24, the conduit 23 being connected with the right end of the cylinder and the conduit 24 being connected with the left end of the cylinder through a conduit 25. A control or rudder bar 26 is pivotally mounted on a bracket 21 on the valve 5 by means of a pivot pin 23, rotation of the bar yabout the pin serving to selectively depress the plunger 2I or the plunger 22, The valve mechanism 5 is of the duplex type having a pair of self-lapping valves operated respectively by the plungers 2| and 22, and it will be understood that on operation of the rudder bar to depress the plunger 2I, the corresponding valve mechanism will be operated to supply fluid pressure to the right end of the cylinder t aty a pressure substantially proportional to the degree of movement of the rudder bar to the position shown, while on movement of the rudder bar in the opposite direction from the position shown, a graduated and controlled pressure will similarly be supplied to the left end of the cylinder.

The actuating mechanism for the device 9 is. similar tovthat set forth in applioants copendingapplication Ser. No. 590,672, which Was iiled inthe Patent Om-ce on April,27, 1945, and this invention isparticularly directed to the locking means shown for controllingthe movement of the device 9 under the control of the actuating control mechanism.

With regard to the construction of the valve mechanism 5, it will be noted that the mechanism operated by the plungers 2I and 22 is identical on both sides of the valve, and the right hand portion of the valve will therefore'be described. In addition to the inlet chamber It, the right hand portion is provided with an outlet -chamber 29 connected with the outlet conduit 23, and separated from the inlet chamber by means of a ported partition 30. An inlet and exhaust valve assembly comprising an inlet valve 3l, a stem 32, and an exhaust valve 33 on the upper end of the s-tem, is normally maintained in the position shown to prevent communication between the inlet and outlet chambers through the ported partition by means of an inlet valve spring 34 interposed between the exhaust valve and the upper surface of the partition. Operation of the valve assembiyis accomplished the exhaust valve and subsequently open the inlet valve in order to admit fluid pressure from the inlet chamber to the outlet chamber, and

'due to the fact that the outlet chamber is connected with the control chamber 39 through the restricted passage 4 l, the pressure supplied to the outlet chamber and the control chamber will p eventually exert sucientforce on thediaphragm to overcome the force exerted by the graduating spring, whereupon the valve operating element will be moved upward sufliciently to permit the the outlet chamber 29 by means oi a restricted passage 41 in such a manner thatthe lower surface of the diaphragm is subjected'at all times to the pressure in the outletchamber, the exhaust chamber being connected with atmosphere by means of an exhaust port 42. In ordeixltrzattheV valve operating element may be actuated by.

means of the plunger 2l, la graduating spring 43 is interposed between the upper surface of the diaphragm and the lower surfaceV of a washer "slidably mounted on the plunger and in engagementwith a shoulder 45 lformed on the upper end of the plungenthe result being that on down ward movementv of theplunger, the graduating spring is compressed inV such a 'manner as to impose a downward force on the diaphragm which tends to correspondingly move,V the element 35 downward into` engagement with the exhaust valve 313..l Upward movement of the washer d'4 onthe element 35 lis-restrictec'i'by the flange 55, andit willibe understood that with `thisV construction, thegraduating spring 43'may be vinitialiy instaiieain suon a manner as tot@ slightly compressed between the upper surfaceof the diaphragmand the lower surface of the washerl in such a manner that initial operation of the pluifigerY 2l will cause the valve mechanism to immediately deliver'a pressure corresponding to the'degree of precompression ofthe graduating spring', it being'understood that on downward movement of the valve operating elementy '3i subsequent to closing of the exhaust valve, the-inlet valve 37| 'will be moved to open position to establich Comunication between'v inlet chamber la and outlet chamber 292 It is pointed'out in this connection,- that the operation of the self Ylapping valve mechanismjust described, is substantially identical with that disclosed in the .paten't'to William J. Andres and Roy S.- Sanford, No. 2,133,275; issued October l'S, 1938, but it isalso pointed out' that if desired, the graduating spring may be soV dimensioned with respect to the position o'i the diaphragm and the washer M as to `avoid any preloading or initial precompression of the graduating spring during installation.y The lower portion of'the plunger 2|V is provided withA a skirtlidwhicl'i isV guided by means of'a bore 41 formed 1in the Casing of the valve, and communication vbetween the exhaust port 42 and the exhaust chamber lic is permitted by'means of a port a8 formed-inthe wall or the skirt. Thus the-operation of this controll valve is substantially .identical` with' that described-'and disclosed ifn'Fig 1 of the 'above referred 'to patent, and? it will befapparent that witnth'e plungeral'in the positionshown, commu'x'iicationbetween the inlet chamber Wand the outlet'chainber 29Y will be prevented, while communication will be Vperirlittedb'etweenthe outlet' chamber' andatlnospherethrough the bore 35, ports 48 ofmed inthe Wall ofthe bore; exhaust chamber le, and ports. and 42. On downward movement oi the plunger, the valve operatingelement will be moved. downward to first :close closing of the inlet valve in order to maintain the pressure in the outlet chamber substantially proportional'to theVV degree of movement of the plunger 2l' from the position shown. In like manner,V the left' hand portion of the valve Vmechanism 5 is provided with an outlet chamber 5o, inletand exhaust valves 5| and 52; a valve operating element 53, a pressure responsive diaphragm 54 connected therewith, and a graduating spring 55 interposed between the plunger`22 and the i diaphragm,l and since theplunger and valve operating element are constructed-in the same'manner asxthose'shownfin the righthand portion ofthe'valve, it will'be understood that with the plunger in the postionshown, the outlet chamber will be in communication with atmosphere througha bore 55 formed in theplunger, ports 56 formed inthe wall of the bore,- an exhaust chamber lformed inthe casing, a port'58 formed'on theA lower portion of. the plunger` 22, and an exhaustport 59 4formed in thevalve casing. .'Since-tlie'outlet` chambers 29 and 5= are connected with the right and left ends of the cylinder 20 through conduit 23 andconduitsd and 25 respectively, itwill be clear vthat the'valve mechanism 5 may be operated. by the rudder bar` '26 to supply any desired pressure to either end of the cylinder, this pressure beingsubstantiallyv proportional to the degree of movement of the rudder bar from the position shown in either direction dependingon which end of the cylinder is 'to beenergized by the operator.

The valvemechanism-8 is similar to` thevalve mechanism 5' exceptI for ,the omission of.v the graduating springs, andA is likewiseof thefduplex type; Sincetheupperfand lower'halves of the valve, are y of identical: construction, i. they upper halfv only is showninV sectionkv and will-be dez scribed in detail. -As shown in the4 drawing, the valve mechanism is provided with a casing BU, the upper portion of-whichis provided with an outlet chamber 6|; a diaphragm or control cham ber E2, and an exhaust chamber 63, the latter being provided with' anvatmospheric-port 64; A ported partition 65 separates the inlet` chamber I8' from the outlet chamber. 6|, communication` between these chambers through the partition being normally prevented by means of an inlet valve 68 having a stem- 61 and an exhaust valve 'carried-on theleft endfof the stem, the valve. assembly thus formed being normally maintained in the position shown to prevent communication between the inletandoutlet chambersthroughthe ported partitionby means of aninlet valve spring 69-interposedrbetween the left surface ofthe partition andthe rightiside of "the-'exhaust valve. The left end of the outlet chamber .BYI is defined' by meanscf apartition '10 formed the casing, and the outlet chamberV communif. ca'tes with the diaphragm chamber. 62 .through a restricted passage 'H formed-in the above parti--l tion. Ava1ve operating element.- 12 islslidablyQ mounted in thercasing as shown, the element be-` ing providedY with a central bore 13, `and beingA adapted on movement to the right to contact the exhaust valve in order to prevent communication between the outlet chamber and the bore. The bore 13 is adapted to communicate with atmosphere through ports 14, exhaust chamber 63 and an exhaust port 64 formed in the casing. A ilexible diaphragm 15 serves to separate the dia phragm and exhaust chambers, the diaphragm being suitably clamped to the casing at its outer periphery, and at its center to the valve operating element. A valve operating plunger 16 is slidably mounted in the casing, and a shoulder 11 formed therein serves to engage the left end of the valve .operating element. A port 1'8 is formed in the plunger as shown in order to insure communication at all times between the exhaust chamber and the exhaust port 64. Thus with the valves in the position shown, communication is prevented between the inlet and outlet chambers and is permitted between the outlet chamber and atmosphere, thus the bore 13, the ports 14, the exhaust chamber 63, the ports 18 and the exhaust chamber 63, the ports 18 and the exhaust port 64, while on movement of the valve operating element to the right, the right end of the bore 13 is closed by the exhaust valve, and the inlet valve 66 is subsequently moved to open position in order to permit communication between inlet chamber I8 and outlet chamber 6|. Since the diaphragm is subjected at all times to the pressure in the outlet chamber through the restricted passage 1|, it is apparent that this pressure will act on the diaphragm to move the valve operating element to the left as soon as the diaphragm force is suicient to move the element against the force exerted to the right thereon. The lower half'of the valve mechanism is provided with a similar valve operating plunger 19, the lower portion of the mechanism being adapted with the plunger 19 in the position shown, to prevent communication between the inlet chamber I8 and a flexible outlet conduit 88, and to permit com munication between the conduit 88 and an exhaust port 8| formed in the casing of the valve mechanism.

The valve mechanism 8 is arranged to control the supply of fluid pressure to the uid motor 1, the latter motor including a casing 82 having a piston 83 slidably mounted therein. The casing ispivotally mounted on the structure of the airplane by means of a bracket 84, and the left end of the casing 82 is connected withthe upper outlet chamber 6| of the valve mechanism 8 by means of a conduit 85, a conduit 86, and a flexible conduit 81 connected with the outlet chamber. In like manner, the right end of the casing` is connected with the lower outlet conduit 88 by meansof a conduit 88. It will be understood that on movement of the plunger 16 to the right, fluid pressure will be supplied to the left end of the motor 1 from the reservoir through conduit I8, conduit |9, conduit 28, inlet chamber |8, ported partition 65, outlet chamber 6|, and conduits'81, 86 and 85, while on movement of the plunger 19 to the right, the valve mechanism will serve to supply fluid pressure from the reservoir to the right end of the motor through conduits I6, I9 and 28, the lower portion of the valve mechanism 8, and conduits 88 and 88, while with the parts in the position shown, both sides of the motor 1 are connected to atmosphere through the passages heretofore described.

In order that the fluid actuators or motors 6 and 1 may be effective to control the actuation of the device 9, a lever 89 is pivotally mounted gage a flange ||6 formed on the casing.

on the casing of the valve 8 by means of a pivot pin 98, the lower end of the lever being connected to the piston 83 and a piston rod 9| connected thereto, by means of a pivot pin 92 and a slot 93 formed in the lever, the upper end of the lever being connected with a piston 94 slidably mounted in a cylinder 95 of the fluid motor 6 by means of a piston rod v96 connected with the piston and connected with a slot 91 formed in the lever -by means of a pivot pin 98. In the particular embodiment of the invention shown, the pistons 83 and 94 may be so designed as to have equal areas, and the lever 89 is divided into lever arms 99 and |88 above and below the pivot pin 98 respectively, these lever arms being preferably of equal length. Consequently, when equal pressures are applied to the pistons 83 and 95 to move them in the same direction, the forces acting on thelever arms 99 and |88 to rotate the lever 89 about the pivot pin 98 will be balanced, and no rotation of the lever will occur under this condition of operation. In order that the power delivered to the uid motors'6 and 1 may be effective to move the device 9, a connecting rod 8| is threadedly received by the casing of the valve 8 as indicated, and is connected at its right end to a lever arm |82 carried on the device by means of a slot |83 and a pivot pin |84'. Means is also provided to normally maintain the device 9 in a neutral position, this means being included in the neutralizing mechanism |8,'and

comprising a casing having a collar |86 slid-- ably mounted therein and connected with the rod |8| for movement therewith. Neutralizing springs |81 and |88 are interposed between the left and right ends of the casing and flanges |89 and ||8 of spring cages and ||2 slidably mounted in the casing. The cage is provided with a flange ||3 adapted to engage a shoulder ||4 formed in the casing to prevent further movement of the spring cage to the left, while movement of the spring cage ||2 to the right beyond the position shown is prevented by means of a flange H5 formed on the cage and adapted to en- The springs |81 and |88 are preferably installed in a precompressed or preloaded condition'in -order that a predetermined force may be required to move the collar |88 and the rod |8I in either direction from the neutral position shown t0 effect movement of the device 9.

In the event the operator is desirious in turning the rudder in a clockwise direction, for example, the rudder bar 26 may be rotated in a counterclockwise direction to depress the plunger 22, whereupon the graduating spring 55 is coinpressed to move the diaphragm and the attached valve operating element 53 downward to close the exhaust valve and open the inlet Valve 5| in order to permit iiuid pressure to be supplied from the reservoir 4 to the left end of the iiuid lmotor 6 through the passages heretofore described. When this occurs, the piston 94 and the rod 96 move to the right, tending to rotate the lever 89 about the pivot pin 98 which causes a slight movement of parts 83 and 9| toward the left. This action moves the plunger 18 to the right to close the exhaust valve 68 and open the inlet valve 66, whereupon fluid pressure is supplied to the left end of the motor 1 through means already described. As the pressure increases in the left end of the motor 1, .the piston 83 and the rod 9| are moved tothe right, thus tending to rotate the lever 89 in a counterclockwise direction about the pivot pin 98 to move the casing of valve '8.

7 to the-right, and to eventually perm-it mov-,ement of the plunger -16 to the left ,with respect to the casing of the-valve 8 su-fcientlysto permit closing ofthe inletvalve 56. men this waive closes, the valve kmechanism .is inlapped position and a pressure is maintained :in the def-t end of the-finotor which issubstantially equal `to that obtaining in the left end of the motor -6 due-to the balancing action inserted fby the ,lever 819. It is also pointed out that .during the lalcove operation, force is .exerted on the casing of the valve 8 through the pivot .pin d by the fact-ion of the motors -B and 1 to move the entire valve :asse-mbly to the right, and sincethe latter-is connected with the lever |0,2by means of fthe-rod 40d', the device 9, which -is pivotally -mounted -I'or .rot-ation on -a shaft-4H, is rotated in a clockwise direction. -In like manner, on rotation of the rudder bar 26 in the reverse direction, the grlunfger 2| is depressed, and uid pressure is supplied to the right end of the motor e, whereupon the lower portion -of the valve mechanism S-yis operated to supply ilu-id pressure tothe right end ofthe motor in the manner above described, and through the previously `described passages. Thus lwhen the valve mechanism 8 has been moved-to lapped position due to the balancingv of the pressures `in the. motors `l .and l, due to the balancing vact-ion oi `the lever 89,-, it will be apparent .that the application of an outside fierce l'to the device tending-,to -move the latter -in one direction or the other will move the entire mechanism comprising theconnecti-ngrod |0|, the; valve mechanism 8, the lever 88, and piston rods B6 and 5l :as well as pistons 94 and 83 in 'a corresponding direc tion, without in any way operating the mechanism of the valve 8 to vary the pressure cond-itions existing in vthe-motor 1, this being partic ularly true in the event the fluid utilized is ci a compressible type such as compressed air. The advantages oi this type of construction have-ra1- ready been pointed out in the copendingfapplication, 4above referred to, but -it is. also-pointed out that, particularly in the event a Lcompressible medium isused as above stated, it is Jdesirable to provide-means for lock-ing `,the device :8 in any position to which it may have beenmovedthe operation of4 the control mechanism-herein bef-ore described.

In order that the above desirable result may be readily accomplished, a: doublev acting -hy-v draulic device is provided .comprising a Vcasing 8 having a` cylinder H9 and -a piston |20 slidably mounted therein and mounted on a piston rod |2| slidably mounted' in bores |22 Vand |23 i-ormedin thev right and left Aendv walls of the casing respectively. Leakage at these points is prevented by means .of suitable seals |26 and |25, and meansareprovided forbypassingl a hydraulic fluid |26, with whichthe hy draulic device is nfilled, from oneV side of the device to the other through a conduit |-2| .connected to the right end ofV the device, a conduit |28 connected to the left end of the devcaandachamber |29 formed in the hydraulicjcontrol device |2, and likewise completely lled with hydraulic duid, the above chamber serving -to interfconnect the conduits '|21 andy|218. `,A hydraulic .control valve |30 Vis s'lidabl'ymounted 'in the chamber |29-, this valvebeing in theform of a pistonpadaptcd in the position shown to preventcommunication betweenconduits |21 and |28, andl being provided with ports |'3| therethrough in order to lperm-it the flow orhydraulicnid-from one side ofthe valve to another on movement of the latter :in

either direction from the position shown. The valve is provided with upward and ndowrrw.ardly extending stem portions |32 and |133., and Athe valve is normally maintained inthe =closed posi,a tion shown by means `0|? springs |34 and |35 interposed between the casingand-flanges |55 and |31 `formed on the upper and lower p'ends respectively of the stem portions |32 and |33. The upper end ofthe cont-rol .device -|2 isdividedinto atmospheric .and control chambers |38 and v|39 by means of a flexible diaphragm '|40 clamped in the casing and attached at Aits center to theva'lve stem portion |32,-the lower end of the casing being similarly divided into atmospheric `and control chambers |'4I and |42 .by means` of -a diaphragm |43 clamped in the casing and fat'- ta-ched at its center to the lower end fof "the valve stem portion |33. The atmospheric :chambers `|38 and |49 are provided with atmospheric ports |44 and |45 and leakage betweenthe chan ber |20 and the atmospheric chambers ,is pra vented by suitable seals |46 and v|41, associated with the upper and lower valve stem 'portionsas shown. n 1

In order that the mechanism .|2 .may be *eiec* tive to control the bypassing f hydraulic :duid from one side of the hydraulic locking-device j'H to the other side thereofwhen it is udesired to eiect movement of the device 9 Vto a new position, the system is so constructed as "to subject the control ychamber |39v at all times-to the pressure supplied to the fluid motor while ther control chamber |42 is subjected at all times to the pressure supplied to the uid motor (i.n end, a double check'valve m8` of conventional design, is provided with a bore |49 connected at its lupper end with the right end of 'the motor 6 through a conduit |50 anda portion of conduit 23, and atits lower end with conduit 25, which in turn is connected to the left end of the motor E. A piston IEI is slidably mounted in '-thebore |49, and on application of fluid pressure -to the bore |49 Vthrough the conduit |50, the piston "|51 moves downward to preventcommunication 'between the bore |49 and the conduit 25, Vthe reverse action taking place whenever uid pressure is admitted to the bore from the conduit `25. 'Thus' the piston |5|' is always moved to the 'end .of the bore receiving the lowest pressure, and the center portion ofthe bore is connected with the control chamber |42 of the mechanism I2 by means of a conduit |52 as shown. In like manner, a double check valve |53 having a bore |54 and a piston |55 slidably mounted therein is provided, 'the upper end of the bore being connected at all times with the left end of the motor through conduit 85, and the lower endbeingconnected with the right end of the motor through a conduit |56'an'ci: the conduit 88. "s:

Since the cylinder H9, the conduits |21 .and |28, and the chamber |29 arercompletely illled with hydraulic fluid, it will be understood that with the parts inthe position shown on the draw-- ing, it will be impossible for movement of .the device 9 to occur unless hydraulictfluid is :by-A passed from one side of the cylinderto another through the conduits |27 and |28 and through the chamber |29, but "this action -isprevnted by the valve |36 in the position shownxand consequently the device 9 islocked against move-y ment'by virtue of the fact that itis connectedvalve mechanism 8 and the piston rod 12|.

it is desiredvto move the device 9 in theclockwis'c;

direction, for eiiaiiiple, the rudder bar 26 is moved in fa counterclockwise. direction, operating the valvemechanism to supply fluid pressure to the left end of the motor 6 in order to move the piston 94 to the right end to rotate the lever 89 in a clockwise direction about the pivot pin 90 to operate the upper portion of the valve mechanism 8 topsupply fluid pressure to the left end of the motor- 1. Since it is impossible for the valve mechanism 8 to supply uid pressure to the left end=of the motor 'I until movement of the piston 94 has occurred to effect operation of the valve mechanism 8, the pressure in the left end of, the motor 6 will start to increase before a similar increase in pressure occurs in the left end of the motor'l. The Ipressure supplied to the left end of the motor 6 is transmitted to thel control chamber |42 of the control mechanism I2 through conduit 24, conduit 25, double check valve |48 and conduit |52, .while the pressure supplied to the left end of themember 'l is transmitted.` to -the control chamber |39 through conduit 86, conduit 85, double check valve I 53 and a conduit |51 connected between the bore I54'of the double check valve and the Vcontrol chamber |39.` `Thus `an increase in pressure occurs in chamber |42 prior to a similar increase in the chamber 39, with the result that the upward force exerted by the diaphragm |43 is greater 'than the downward force exerted by the-diaphragm |40, and the valve |30 is moved upward out of register with the upper ends of the conduits I'2| and |28, permitting hydraulic fluid to be bypassed from the right end of the cylinder I9 to the left end through the conduits |21 and |'28 and chamber |29, and permitting movement of the device 9. As heretofore stated, the pressure eventually increases in the left end of the motor 1, moving the piston 83 to the right in order to move the control valve mechanism 8 to the right and in order to rassist in moving the device 9 in a clockwise direction from the position shown. The pressure will eventually reach substantially the same value as the pres sure in the left end of the motor 6, a-t which time, the pressures will likewise equalize inchambens |39 and |42, and the valve |30 will again be moved to the closed position shown by vthe action of the spring |35, whereupon the hydraulic locking device is again elective to -`maintain the device 9 in the new position. Y In the event it is desired to move the device 9 in the opposite direction from the position shown, the rudder bar 26 is moved in a clockwise direction', operating the valve mechanism to supply uid pressure to the right end of the fluid mot-or Band to the control chamber |42 of the mechanism I2 through ythe double check valve, the pis ton in this case being moved downward to prevent the ilow of fluid pressure into the left end of the motor 6 through the conduit 25. The pressure thus supplied to the chamber |42 again moves the valve |30 upward to permit hydraulic fluid 'to be bypassed from the left end of the hydraulic locking cylinder |I9 to the right end thereof, and subsequent operation of the valve mechanism 8 by the rocking of the lever 89 will increase the pressure in the right end of the motor and this pressure will Ibe transmitted to the control chamber |39 through conduit 88, |55, double check valve |53 and conduit |51, thus equalizing the pressures in thecontrol chambers |42 and |39, and per-` mitting the valve |30 to again be turned to closed position by the action of the spring |35. Un-

der '.'these circumstances, the device 9 will agairi be locked :in position'by the action of the hy-V draulic locking device, and if the rudder bar 26 is now moved slightly in a counterclockwise direction to operate the valve mechanism 5 to release fluid Apressure from the right end of the motor 6this decrease in pressure will immediately-be reflected in the control chamber |42, and due tothe fact that the pressure in the right end ofthe motor 'l'.and in the control chamber I39will be maintained at its previous value until the valve mechanism 8' is operated `by the piston 94 and the lever 89 to release fluid pressure from the right end ofthe motor the drop in pressure in the control chamber |42 will permit the diaphragml to move the Valve I 30 downward to. establish communication between conduits |21 and |28, and sinceunder this condition of operation, the spring' |08 in the device l0 has been compressed, and tends to move the collar |09 to theright toward neutral position, such movementl to Athe right will cause hydraulic fluid to be bypassed from the right end of the cylinder ISIS tothe le'ftv end through the conduits |21 andthe chamber |29, this bypassing action continuing until the pressures in the cylinders and inlthecontrol chambers are again substantially equal, `whereupon'the valve |30 will be again returned to closed position by the action of the spring |34. It is valso desirable to insure operationA of the device 9 inthe event of failure of theuid pressuresupplied to the fluid motor 1, and to this end, stopsV |58 yand |59 are provided on the casing of the valve mechanism 8 for the purpose of limiting lrotation of the lever 89 in either direction about the pivot pin 90. In the event of failure of the fluid pressure supplied to -the motor l, the'motor will be ineifective to oppose rotation ofthe lever 89 by the action of the'vmotor 6, but it will beunderstood that as soonas the lever 89 is rotated to abut the stop I 58 or the stop |59 as the case may be, the motor 8 will bei eiective to move the entire valve mechanism'bodily in one direction or the other with consequent correspondingmovement of the device 9 about the shaft I|'|. It is also pointed out that under this type of operation, the control mechanism I2 will be operated only by fluid pressure from the fluid motor 6, the application of fluid pressure to either endl of the motor 6 resulting in an immediate increase in pressure in the control 4chamber I 42 and consequently opening of the valve r|30 to permit the bypassing of hydraulic fluid from one side of the cylinder |I9fto the other. Since :there is no build-up of pressure in the motor or in the control chamber |39 under this `,type of operation, the valve |30 will remain open whenever fluid pressure is supplied to the motor 6, and the latter will be effective to operate the device 9 in a directionV determined by the direction of movement of the rudder bar 2 6.

Although the mechanism has been illustrated and described as comprising fluid motors having pressure responsive members of equal areas connected with lever arms 99 and I 00 of equal length, it will be understood by those skilled in the art that lapping of the valve mechanism 8 Ywillbe effected whenever the moments on the lever 89 about the pivot pin 90 are substantially Y facciamo@ the moments about the pivot.- pim will equalize',Y with the pressure'im motor vBig'matenthaxizi'fiat. in motor 'il' Ini this erfenis; itis-contemplated: thatY the area ofi diaphragm; H3 will: be correr-'1 spondingly reducedl withf respect` tothat: ofY diaphr'agm lll-iL. insuring maintenance: of` the' valve i3d in the position shown'A wheny the pressures in motors s andflV areso adjusted astoequalizing ofA the moments aboutl the. pinfl 91h and` thatfin* any case; the areasof1the-diaphragmsfM0' and* 43* will be so` chosen as? tor insureV the imposing;

of equal and opposite: forces: ons thef valve' Idil."-

when the pressuresfin the' mctorslfand laretsuch: that the' moments on the-lever are equalv and opposite; In' like mannen;` pressure' responsive members in the motors Gand 1. hav-ingequalfareasf may be connected to lever armsof unequallengthy on either side of thepivot:` pin 90;, and the-rela# tivei areasof thev diaphragme' M0 and M3? correspondingly adjusteditofinsure positioning.ofthe'-` valve i353 as shown whenthevalvermeclianismi 8* is lapped bythe operatiomofl the leverlkactuated. by motors 6 and:1;

rhere has thus' beenf provided;x in` connection with a control mechanism kor the type hereinw before described, nove1= lockingr meansi controlled entirely by variations inV ther pressure of fluid supplied tothe motors? or actuators En and 'Ilforpermittingor preventing4 movement. of the de-- vice il, and for denitely preventing suchy move-A ment by outside forceswhen the; moments act-- ing on the lever` 89- are substantially equalizedr and the valvesof thefcontrol: valvemechanism 8,- are in lapped position.

While the mechanism-showgirl: the drawing has been described in1considerable detail,- itbeunderstood that numerous changes may be made in the constructionl Witt-uint'- departing in any manner from the-spirito the inventiom andthat the invention isinotl limited toi the; formsshown butA may receivea variety: ofi mechanicalexpressions as will-readilyappear tothose'skilled inthe art. Reference. will,v therefore, bei hadfto said device in accordance variations; in the" degree of power supplied3 to said actator iii-'- cluding a hydraulic device afprs's'uif-re sponsive member subjectedto a col' of hy; draulic fluid and connected witl-'the Vfirs -nai'nredl device, means for controlling tlie 1'"noi/e'ie'iitfV of said column of? hydraulic iiid by said" pressure' responsive member, adme'ans r'spori's'i 'otlie power supplied toI afftuato'ifs'k for controlling' the operation of the" last nmed controlling m'eaS'- 2. In a power controliniiecfais'ii" of ther typehaving a deviceY to be acti'ia't'ed,` a pair oi power actuators for actuating the device, power*corr-Av trol means for controlling the'l supp'ly`r of power to' one of the actuators, power control means' con;

trolled by the o'peiato'of saidlponA actuator for controlling the supply' of power to the other' of" l2 saidactuators,:andcnnectlnafmeans for connecte-'- ingsaidfv actuatorsf and: device? andi 'for operatlng thez second; named: power' contrer meansxlockaf ing means for controlling the' movement off said! e device in accordance with, the degree of power. 7

supplied to; each ofi said actuators? including: a: double acting hydraulic devicefhaving apressur responsive; member connected with' the;v flrstl named device, means for by-'passin'g hy'olraliliciv iluid from. one side of' the: pressure'- responsive. membert't'o the other, and' meanszrespunsiveto7 theV power suppliedto bothsaidactuators?for conit'rolling; the flow of hydraulic Iiuid icy-passingmeans.

3;.Ina power control mechanism of theftype'f havingV aI device 1 to be actuated, a1. paii'f of po'welr actuators Vfor actuating-fl the? device;l power` conni trol'means for controllingthefs'upplyf of! .powerltm one-of the actuators,` powercont'rol: means-corde trolled by the operation of saidone actuator for: controlling?` the supply of power to ithe othery of: said actuators, and` co'nnectingf means noti' conninecting said actuators and device`v andi for? .open-1:- ating the: secondiV named :powerfcontrol meaii locking means for 4controlling thernio'verraient` ci" saidy device in ac'cordamcei.'with'l the: degree of:v

power 'supplied to-veach ofsaid actuatorsA include"` ingr a double acting hydraulicf device hav-ing ai' pressure responsive member connected Witfhathe'. rst named device, means-for by'passi-ngnhysdrauf lic uid fro'rnoneside; of said pressurerres-pornsiveLV member to the other; meansffror normally prevventingthe--owof hydraulic fluid: throught-said' ley-passing: means, and meansfrespon'sive to the` 35 power supplied-to eachzofly the actuatorsfor open-- eoL ating said flow preventing means` to f permit.` thel iiowA of: hydraulic-,uuid through saintbr-passing: means when the ratio. of the: deg-ree of` power! supplied toi said.r actuators variesfrom a1 prede termined value;

4. Ina power. control-mechanismofs the? type#V having afdevicetobe. actuated-,af pair of power actuators fori actuating-the device,` powen ccn-fk trolvmeansfor controlling. the supply of. power' toT one oi the actuators,l power control means controlledfby the. operation of saidone actuator for controllingvlthe supply of: power toithef. other of' saclfactuators,` andfconnecting means for con-4 necting said actuators and device and for. oper.;v

A ating the. second namedpower' control.Y moanaY locking. means for controlling-the movement o'f said. dev-ice i'n accordance: witlr the degree of power suppliedA to eachoff. said.- actu'atorsvincludey ing. adouble acting` ,hydraulic device -haviiag'a'- pressure responsive member connected with the',- rstnamed device; means for by-passirig-v hy draulic fluid fromonefsideofsaidpressure. re sponsivemember tothe.ot hera valve for conv trolling the flow ofhydraulic. fluidi.thi'ough!said.` by-passing means,..mearisffor normally maintai'n)V ing said-valve inclosed position, and valv e.cn)c'i ating means responsive. to, the'V .powerv supplidi.

to each. of, the actuators: for` moving the? valve to openf` position whenever the ratio-of. theedogree of power supplied tosaid aotuatorsvaries. from a predeterminedvaluel, y

5. linV a--power' control.' r'neclianis'mT for. the: type.v having. a devicetobe. actuated; a pair o'f" power. actuators for actuatingthe.device,.powe'1 coritiiol means for controllingn the fsupplyoi. power! 't'doe of the actuators, pow'encontrol m'e'anscontrolled.-

trolling the supply ofi pwerito' the otlie'i' ci said. actuators, and connecting means'. for. confie iisg;

`means for controlling the movement of said device in4 accordance with the degree of power supplied to each of said actuators including a double acting hydraulic device having a pressure responsive member connected with the rst named device, means for by-passing hydraulic fluid from one side of said pressure responsive member to the other side, a valve for controlling the flow of hydraulic iiuid through said by-passing means, means for normally maintaining said valve in closed position, means responsive to the power supplied to said one actuator for moving the valve to open position, means responsive to the power supplied to thecther of said actuators for moving the valve t-o open position, and means for connecting saidV power responsive means and valve for eectin'g movement of the valve by either of the power responsive means and for preventing movemen-t of the valve from closed position except when the ratio of the degree of power supplied to said actuators varies from a predetermined value.

6. In a power control mechanism of the type having a device to be actuated, a pair of power actuators for actuating the device, power control means for controlling the supply of power to one of the actuators, power control means controlled by the operation of said one actuator for controlling the supply of power to the other of said actuators, and connecting means for connecting said actuators and device and for operating the second named power control means, locking means for controlling the movement of said device in accordance with the degree of power supplied to each of said actuators including a double acting hydraulic device having a, pressure responsive member Yconnected with the first named device, means for by-passing hydraulic fluid from one side of said pressure responsive member to the other side, a valve for controlling the :dow of hydraulic fluid through said by-passing means having a closed position and movable in either direction therefrom to an open position, means for normally maintaining said valve in closed position, means responsive to the power supplied to one of said actuators for moving the valve in one direction from closed position, means responsive to the power supplied to the other of said actuators for moving the valve in the opposite direction from closed position, means for connecting said power responsive means in opposed relationship, and a connection between the last named means and said valve. Y

'7. In a power control mechanism of the type having a device to be actuated, a pair of double acting power actuators each having a power responsive member movable in either direction for actuating the device, power control means for selectively controlling the supply of power to one of the actuators to move the power responsive member thereof in one direction or the other, power control means controlled by the first named power responsive member for supplying power to the other of said actuators to eiect movement of the power responsive member thereof in the same direction as the power responsive member of said one actuator, and connecting means for connecting the iirst and second named power responsive members with the device and for operating the second named power control means, locking means for controlling the movement of said device in accordance with the degree of power supplied to each of said actuators including a double act-` ing hydraulic locking device having a pressure responsive member connected with the iirst position to prevent-,fthe how-of hydraulic iluid through said by-passing means, means for normally maintaining said valve in said one position, a pair of vopposed power responsive means connected with the valve, means for subjecting one of said power responsive means.v to the power supplied to said one actuator to effect movement of the powerv responsive member thereof in either direction, and means for subjecting the other of said power responsive means to the power supplied to the other of said actuators to move the power responsive member thereof in either direction. y

8. In a power-operated control mechanism of the type having a device to be actuated, a pair of uid actuators each having a pressure responsive member for actuating the device, valve means for controlling the supply of uid pressure to one of said actuators, valve means controlled by movement of the first named pressure responsive member for controlling the supply of iiuid pressure to the other of said actuators, and connecting means for connecting the rst and second named pressure responsive members with the device and for operating the second named valve means, locking means for controlling the movement of said device in accordance with the degree of iiuid pressure supplied to said actuators including a double acting hydraulic locking device having a pressure responsive member connected with the first named device, means for by-passing hydraulic fluid from one side to the other of the last named pressure responsive member, a valve operable in one position to prevent the iiow of hydraulic iluid through said by-passing means, means for normally maintaining said valve in said one position, and means responsive to the pressure of iiuid supplied to each of said actuators for moving said valve from said one position to permit the flow of hydraulic iiuid through said lay-passing means.

9. In a power-operated control mechanism of the type having a pair of double acting fluid actuators each having a pressure responsive member for actuating the device, valve means for selectively controlling the supply of huid pressure to either end of one of said actuators to effect movement of the pressure responsive member thereofI in one direction or the other, valve means for selectively controlling the supply of fluid pressure to either end of the other of said actuators to effect movement of the pressure responsive member thereof in one direction or the other, and connecting means for connecting said pressure responsive members and device and for operating said second named valve means, locking means for said device including a double acting hydraulic locking device having a pressure responsive member connected with the rst named device, means for by-passing hydraulic uid from one side to the other of said last named pressure responsive member, and valve means controlled by the pressure of uid supplied to both of said actuators for preventing the flow of hydraulic fluid through said by-passing means except when the pressures supplied to said actuators by the operation of said valve means vary from a predetermined ratio.

10. In a power-operated control mechanism of the type having a pair of double acting fluid actuators each having a pressure responsive member for actuating the device, valve means for selectively controlling the supply of fluid pressure to either end of one of said actuators to effect moves 

